Improvement in slide-valves of steam-engines



UNITED STATES PATENT OFFICE.

GEORGE RIESECK, OF PITTSBURG, PENNSYLVANIA.

IMPROVEMENT IN SLIDE-VALVES OF STEAM-ENGINES.

Specification forming part of Letters Patent No. 38,062. dated March 31, 1863.

To all whom it may concern Be it known that 1', GEORGE R1EsEoK,ot` Pittsburg, in the county of Allegheny, State of Pennsylvania, have invented a new and useful Improvement in Balance Slide-Valves for Steam-Engines; and I hereby declare that the following is a full and exact description of the same, reference being had to the accompanying drawings, making a part of `this specification, and to the letters of reference marked thereon.

The nature of my invention consists in arranging a slide-valve with a top-piece or bonnet, in combination with a exible diaphragm, in such a manner that the valve and bonnet can freely expand and contract, and that the steam acts as well on top as on the bottom of the valve, forming thus a balance-valve, a surplus pressure, however, being exerted by the steam on the top of the valve in order to keep the same down steam-tight on its seat, and, also, that the contactsnrface of the bonnet is kept up steam-tight by a similar surplus pressure of steam.

To enable others skilled in the art to make and use my invention, I will proceed to describe its construction and operation.

In the accompanying drawings, Figure 1 represents a section of the valve, bonnet, steam-chest, and steam-ports; Fig. 2, atransverse section of the same. Fig. 3 is' a horizontal section of valve through the line I II of Figs. 1 and 2. Fig. 4 is a top view of the bonnet.

In all these figures the same letters of reference represent like parts.

A is the valve; B, the bonnet; O, the steamchest; D, the valve-seat, with its port-holes a The steam is admitted through the porthole a under the valve, and communicates alternal'ely with the ends of the cylinder through the port-holes and passages b b', through which.

the steam also escapes from the cylinder into the chest C, from where it is exhausted.

Eis the diaphragm, made of thin copper sheet, vulcanized rubber, or any other suitable flexible material. It is fastened all around its margin to the bonnet by means of the ring c and bolts,I and also fastened and held firmly down on the top surface of the valve by means of a plate, d, and a bolt, f, passing through the body of the valve.' The plate dis smaller than the inside size of the ring c, as clearly shown in 1 and 2, leaving a small portion of the diaphragm (all around the plate d) uncovered and free to yield up or down to a small extent. The bolt f is hollow, forming a small tube, through which the steam in the cavity s of the valve communicates with the space tin the bonnet above the valve. The upper fare of the bonnet is open, a large opening, o o, being cut out of the same.

The action of the steam in the described valve is as follows: The steam enterin g through the port-hole a into the cavity s of the valve will also iill the space t above the valve by passing through. the hollow boltf.

It is obvious that the intermedium of the flexible diaphragm E, made as above described, will not prevent the steam from acting with its full pressure on top of the valve, and the pressure of the steam on the valve from below and from above would be perfectly equal orin equilibrium if the lower surface upon which the steam acts and the top surface were equal; but in order to secure a steam-tight contact between the valve and the valve-seat surface, I make the top surface sufficiently larger to produce such a surplus pressure downward as may be required for the said purpose. It may be well to remark here that the surface on which the steam acts below is variable, de- V pending on the position of the valve, in relation to the steam-ports. Thus, in Fig. 1, the extent of that surface (longitudinally) is from III to IV when in the position of the valve. As shown in Fig. 5 it is from V to VI. In order to keep the valve down steam-tight under all circumstances, the top surface has, therefore, to be made larger than the greatest extent of surface on which the steam acts from below. The steam confined in the space t keeps also the top surface of the bonnet in steam-tight contact with the under surface of the lid F of the chest, by acting on the shoulders g g and the margin h h between the diaphragm and the body of the bonnet, or, in other words, the surface on which the steam acts upward in the bonnet is equal to the whole area inclosed by the `ring c-f-i. e., from VII to VIII-minus the area of the opening o in the top of the bonnet. The size of the opening o o, I proportion so that just a sufficient surface for the action of the steam remains to insure a steam-tight contact of the bonnet and lid surfaces. The heavy pressure exercised by the steam on the top of the ordinary slidevalves, producing a great friction and eonse.

quent loss of power and a rapid Wear of the contact-surfaces, is thus avoided in the described balance-valve, in which the sliding surfaces are kept in Contact with their seatsurfaces, with no more pressure than absolutely necessary to hold them steamftight, whereby the friction and consequent wear of the valve are reduced to a minimum. By the intermedium of the yielding diaphragm the valve and its bonnet are also allowed to eX- pand when their temperature increases and to contract when it decreases without affecting the proper Contact of the sliding surfaces or producing any undue strain on any part. I

wish to state that, although I prefer in the de-Y scribed valve the mode of admitting the steam from below, (under the valve,) it will also answer the purpose of a balaneevalve when the steam is admitted into the steam-chest, as is usually done. In this case there is no steamof steam on the shoulders or tlanges u u of the valve, and the bonnetup against the lid of the chest, by the difference of steam-pressure acting on the shoulders w w upward and on the surface o v downward.

Having thus fully described my improved balance-valve,I wish it understood thatI do not claim providing a valve with a bonnet, as such valves, variously constructed, have been used before 5 nor do I claim the application of aleXible plate or diaphragm irrespective of the particular construction of the valve and bonnet, asY such flexible plates have been used before in balance-valves of a different construction; but

What I do claim, and desire to secure by Letters Patent', is-' Y Constructing and arranging the valve` A, bonnet B, and diaphragm E, substantially as herein described, and for the purpose set forth.

GEORGE RIESEOK.

Witnesses J AMEs M. TAYLOR, Jol-INv C. TAYLOR. 

